Januakt 26, 1917] 



SCIENCE 



87 



hand, the surface tension is negative at the 

 surface of a colloid particle, there will be no 

 flocculation, and the particles will not ap- 

 proach each other near enough to crowd the 

 liquid out of the region of surface energy 

 around either particle. This, of course, does 

 not imply that there is any tendency in the 

 latter case for the colloid particles to remain 

 in equilibrium equally diffused throughout the 

 liquid. Arthur L. Kimball 



Amherst College 



the white pine blister rust; does the 

 fungus winter on the currant? 



In the work carried out in the Province of 

 Ontario during the last two years on this dis- 

 ease, strong suspicions have been aroused that 

 the fungus may in some cases pass the winter 

 on the currants themselves. Several lines of 

 evidence support these suspicions. 



1. The commencement of the currant stage 

 each spring here and there over large areas, 

 without any apparent relation to the pines 

 therein. 



2. The similar yearly recurrence of the cur- 

 rant rust in one particular district ten miles 

 by four miles in extent. In this area (o) the 

 rust outbreaks do not bear any apparent rela- 

 tion to the pines; (&) the pines are very few 

 in number; (c) many lots of these pines are 

 small and their freedom from disease has 

 been established; (d) the evidence from five 

 lots of these young pines growing close to in- 

 fected currants indicates that the rust was not 

 introduced into this area until 1914, and that 

 therefore the prevalent currant stage of 1915 

 and 1916 could not be due to pine blisters, 

 which have not yet had time to mature. 



3. The finding of six cases of the currant 

 stage early in the year from one to two miles 

 distant from any possible source of pine infec- 

 tion. 



4. The occurrence of currant rust in 1916 on 

 two adjacent plants in a large plantation. 

 Early in the year these two only were rusted. 

 The only ■ four plants which were badly dis- 

 eased here in 1915 included these two. 



5. The occurrence of a rust outbreak on a 

 plot of one hundred black currant plants 



which were badly rusted in 1914, and which 

 had been set out in a disease-free neighbor- 

 hood in the spring of 1915 to test hibernation. 



A hypothesis is advanced which gives a rea- 

 sonable explanation of the suspected hiberna- 

 tion. The rust often causes early defoliation 

 of the currant plants, and this defoliation is 

 followed by a secondary production of foliage, 

 due to the development of winter buds. The 

 general occurrence of the rust on these sec- 

 ondary leaves suggests that, allowing for the 

 two weeks' incubation period, the infection 

 must take place very early in their growth, and 

 the question naturally follows: can such 

 started buds be infected at such an early stage 

 in their development that if winter conditions 

 set in soon after, the buds are still capable of 

 surviving? W. A. McCubbin 



Division op Botany, 



Experimental Farm System, 

 Dominion of Canada, 

 November, 1916 



PAMPHLET collections 



To THE Editor op Science: I note in Sci- 

 ence for November 24, an article by Tracy I. 

 Storer from the University of California on 

 " The Care of Pamphlet Collections " in which 

 a type of cardboard case open at the back only 

 and " not larger than 12 X 8 X 2i inches " is 

 recommended for this purpose. Permit me to 

 state that such cases differing only in size — ■ 

 mine are 11 X 7 X 3 inches — have been in use 

 in my department since 1904. Several other 

 departments in the imiversity had such cases 

 made after my design and they have been in 

 rather general use here since. I do not re- 

 member whether the idea is original with me 

 or not. These cases are arranged alphabet- 

 ically by authors and the card index is by sub- 

 ject with the catch word first on the card. 



Chas. B. Moreey 

 Department op Bacteriology, 

 Ohio State University' 



industrial laboratories and scientific 

 information 



To THE Editor of Science : The undersigned 

 committee on engineering of the General Com- 

 mittee on Research, of the American Associa- 



